This invention relates to a chuck, a bit, an assembly thereof, and methods of mounting the bit in the chuck. In particular, this invention relates to the structure of the chuck, the structure of the bit, the interrelated structure of the assembled chuck and bit, methods of mounting the bit in the chuck.
For many years, chucks have been used to grip or mount bits for a variety of purposes, including the mounting of rotary bits for use with a hand or power tool. In many instances, chucks have included a plurality of movable bit-engaging jaws mounted within an opening of a chuck body. The jaws can be manipulated to clamp the shank of a bit which has been inserted into the opening of the chuck. In this manner, the bit is retained with the chuck which, in turn, is mounted on the hand or power tool. The jaws of such chucks may be operated by use of an external implement, such as a conventional chuck key, or by rotational elements on the chuck.
Other chucks of the past were designed to allow the bit to be inserted directly into the opening of the chuck using a direct-insertion mounting technique, whereby the bit is locked in assembly with the chuck by virtue of structure within a body of the chuck and on the bit.
While some of the above-noted chucks are adapted to receive and mount bits by insertion of the bits directly into the bit-receiving opening of the chuck, the opening is typically designed to receive only shanks of bits with a common diameter or size, consistent with the diameter or size of the opening. Thus, a set of bits of different diameters at the working ends thereof would each be required to have a chuck-mounting shank diameter which is the same as the shank diameter of the remaining bits of the set. This leads to a situation where the bit shank, in order to be strong enough to handle the forces and torques imposed on the larger bits of a range of sizes employed, is much larger than needed, and thus uneconomical, for the smallest bits of the set.
Thus, there is a need for a chuck having structure which will facilitate use of the direct-insertion mounting technique for bits having different shank diameters.
Also, with respect to bits which are formed with chuck-mounting shanks of different diameters, there is a need for uniform structure on such shanks to facilitate assembly of each bit with common structure of the chuck when using a direct-insertion mounting technique.
In addition, there is a need for a chuck and bit assembly having structure which facilitates use of the direct-insertion mounting technique where the parameters of the chuck structure are constant and the parameters of the structure of the bits fluctuates.